Nationwide, beach closings constitute a major environmental and public health concern. Recreational water quality is evaluated by measuring levels of bacteria such as enterococci, fecal coliforms, or E. coli, all of which indicate the presence of fecal contamination. In freshwater, the EPA recommends that water quality advisories be issued when levels exceed the guideline of 235 E. coli/100 ml; these levels have been established by epidemiological studies that have shown a correlation between concentrations of indicator organisms and gastroenteritis. The health risks associated with exposure to fecal pollution are different depending on the source of contamination. We have found that levels of E. coli in recreational water are highly influenced by localized contamination from roosting birds, and many times are not a reflection of serious contamination events that present a known health risk, such as human sewage overflows. Gulls, the most prevalent type of coastal aquatic bird and waterfowl, are known to carry human pathogens such as Salmonella and Campylobacter. The potential for beach areas to act as reservoirs for human pathogens is not known. In addition, the relationship between levels of human pathogens introduced into surface water by gulls or waterfowl and those of indicator bacteria is not well established. We will evaluate human health risk at beach sites that have experienced chronic beach closings due to localized contamination. In these studies we will 1) determine pathogen occurrence in gull populations that inhabit beach areas, 2) develop direct detection methodology for pathogens that can be applied to recreational water samples, and 3) perform pilot studies to determine the potential for avian adenovirus to be used as a specific marker for avian fecal pollution. Basic information as to the occurrence of human pathogens in beach ecosystems is essential in order to design further studies to assess human health risk, determine parameters that influence transport and fate of these pathogens in the nearshore environment, and finally, develop assessment tools that can discern the sources of fecal pollution.